Masters Degrees (Genetics)

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Browsing Masters Degrees (Genetics) by browse.metadata.advisor "Bester, Cecilia"

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    Genetic marker resources for application in Cyclopia species
    (Stellebosch : Stellenbosch University, 2016-12) Niemandt, Marione; Roodt-Wilding, Rouvay; Bester, Cecilia; Tobutt, Kenneth; Stellenbosch University. Faculty of AgriSciences. Dept. of Genetics.
    ENGLISH ABSTRACT: Cyclopia species are endemic to the Fynbos Biome of South Africa and have been utilised for many years as a health drink known as honeybush tea. Despite the commercial importance of Cyclopia, no molecular resources are available to characterise this genus. The polyploid nature furthermore limits the use of molecular markers as some species exhibit up to 14 sets of chromosomes (Cyclopia intermedia and Cyclopia meyeriana: 2n = 14x = 126). This study optimised a DNA extraction protocol for various Cyclopia species in order to obtain high quality DNA as the first crucial step during molecular genetic studies. The use of young, fresh leaves as starting material for DNA extraction presents a challenge when sampling from distant locations; therefore, a CTAB/NaCl buffer was optimised to preserve the leaves for up to two weeks prior to DNA extraction under laboratory conditions. Microsatellite markers were developed in the commercially important C. subternata and transferred to six other Cyclopia species with a success rate of 81-88%. The Agricultural Research Council (ARC) maintain a field gene bank for several of the Cyclopia species and a set of six DNA fingerprinting markers were developed to characterise the accessions. This will facilitate the correct management of the gene bank, such as keeping track of clones for seed orchards or commercial release and the identification of duplicates in the gene bank. The genetic diversity of C. subternata wild populations was investigated and compared to the accessions to ensure that the gene bank accurately reflects the natural diversity. As such, the C. subternata accessions were representative of the wild samples, excluding the genetically distinct Haarlem population. The genetic resource tools developed in this study can be applied to detect the extent of cross-contamination of cultivated material to wild populations of Cyclopia as well as the characterisation of wild populations of all known species that could be included in the field gene bank. Further conservation strategies include the monitoring of wild-harvesting as well as the in situ conservation of genetically distinct populations.